This invention relates to the field of intraluminal catheters, and more particularly to an intraluminal catheter for cannulation of a patient""s body lumen for delivering or draining fluids.
The use of intraluminal catheters in a patient""s body lumen often requires securing the catheter so that its distal or operative end is at a desired location inside the body lumen. Means for securing the catheter within a body lumen include purse string sutures, and balloons. When using purse strings, the vessel is usually clamped to stop the flow of fluid inside it. The clamping procedure makes purse strings complicated to use in percutaneous or minimally invasive surgical techniques. Moreover, the clamped site, which must be in close proximity to the cannulation site, may cause trauma to the vessel wall or dislodging of calcium debris or plaque within the vessel.
Use of a balloon on the catheter to secure the catheter within the patient""s body lumen may also cause trauma to the lumen, due to the inflation pressure inside the balloon necessary to hold the catheter in place. Moreover, the retention balloon must have a large surface area in contact with the body lumen, for there to be sufficient frictional resistance to prevent catheter displacement. As a result, the large retention balloon is likely to block the opening to nearby branch lumens which intersect the cannulated lumen. Additionally, by using a balloon to both secure the catheter within the body lumen and occlude the lumen, the occluder cannot be displaced relative to the secured site to find the optimum occlusion site. Moreover, because the inflated balloon does not allow for flow of fluid around or across the balloon, the cannulated lumen is obstructed by the balloon, and the catheter cannot be used in procedures where occlusion of the vessel is not desirable.
In some procedures involving cannulae, it may be desirable to occlude the cannulated vessel. For example, during heart surgery, the myocardium is protected by a technique known as retroperfusion in which cardioplegic solution is infused in a retrograde manner (through veins opposite the normal blood flow direction) into the coronary anatomy via the coronary sinus. Retroperfusion requires occlusion of the coronary anatomy to prevent back flow of the cardioplegic solution into the right atrium. On current retroplegia cannulae designs, a balloon is used to retain the cannula in place inside the patient, and also serves to occlude the cannulated vessel. The retention balloon of the current cannulae inflates inside the ostium downstream of the middle cardiac vein (serving the right ventricular territory), in the space between the middle cardiac vein and the veins coming from the left ventricle, and the solution is infused distally to the balloon. Because the space upstream of the middle cardiac vein between the ostium and the middle cardiac vein is too small to contain the balloon, the middle cardiac vein must be excluded from the perfusion. Consequently, the right ventricle is left unprotected during heart surgery. Therefore, although vessel occlusion may be required in a procedure, use of the inflated retention balloon to occlude the vessel is disadvantageous.
Attempts to improve the catheter design to minimize the obstruction the branch lumens have included shortening the retention balloon. Although the use of protuberances or ridges on the balloon surface to improve the frictional contact has been suggested, the shortened balloon may provide insufficient frictional contact with the lumen surface. Fixation balloons made of an open open-walled element material are also known, wherein fluid is free to flow through the open-walled element.
What has been needed and heretofore unavailable is an intraluminal catheter with a securing member which allows for the free flow of fluid around and across it, and with a cannula and an occluder that can be positioned independently the secured site. The present invention satisfies these and other needs.
The invention is directed to an intraluminal catheter having an expandable tubular open-walled element for securing at least part of the catheter within a patient""s body lumen. The intraluminal catheter of the invention generally comprises an elongated shaft and a tubular open-walled element secured to the shaft, wherein the tubular open-walled element is at least in part expandable from an unexpanded diameter configuration to a larger diameter expanded diameter configuration within the body lumen. Upon expansion, the tubular open-walled element is configured to contact a wall defining the body lumen and thereby secure at least part of the catheter within the body lumen. A cannula member, used for delivering or removing fluids from the body lumen, is slidably disposed within a lumen of the shaft and a lumen of the tubular open-walled element.
In one embodiment of the invention, the catheter shaft comprises an outer tubular member and an inner tubular member slidably disposed in a lumen of the outer tubular member. The cannula member is releasably secured to the inner tubular member, and is disposed in a lumen therein. The tubular open-walled element is secured to the inner tubular member, so that when the cannula member is secured to the inner tubular member, the cannula member can be secured within the body lumen by the expanded open-walled element. However, when the cannula member is released from the inner tubular member, it is longitudinally displaceable relative to the inner tubular member. Therefore, the cannula member can be positioned in one or more optimal perfusion locations within the body lumen during use, independent of the secured site, and then releasably locked into position on the secured inner tubular member.
In one embodiment of the invention, an occluding member is slidably disposed a lumen of the shaft. In a preferred embodiment, the occluding member is on the cannula member. However, it can be secured to the inner lumen of the tubular open-walled element instead. When occlusion of the axial flow is necessary, the occluding member may be reversibly deployed so that it expands inside and against the expanded tubular open-walled element. Because the cannula can be moved freely in the axial direction, the occluding member secured thereto can be positioned in the desired site by pushing or pulling the cannula. The optimal occlusion site can be chosen independently of the secured site, and the occluder and cannula secured within the body lumen by being releasably secured to the secured inner tubular member. The secured cannula member can then be used to deliver or remove fluid from an area of the body lumen sectioned off by the occluding member.
However, where such displacement of the occluding member relative to the tubular open-walled element is not required, the inner tubular member is omitted. Thus, in one embodiment, the catheter comprises an elongated shaft, and a cannula member having the tubular open-walled element and the occluding member secured thereto, with the cannula member slidably disposed in the lumen of the elongated shaft.
The open-walled element material allows fluid to flow freely around and across the open-walled element, and generally comprises a mesh structure or a permeable material. Because the open-walled element does not restrict fluid flow, it can be deployed over lateral branches intersecting the patient""s body lumen without obstructing the lateral branches or the coaxial flow around the cannula. Unlike fixation balloons which do obstruct flow within the body lumen, the length of the open-walled element does not have to be minimized to avoid obstructing the flow in the body lumen and side branches. Therefore, the open-walled element can be as long as necessary to obtain good support, and minimizes pressure on the vessel wall. The open-walled element may be made of a variety of expandable materials including but not limited to polymeric materials, stainless steel, a NiTi alloy, a pseudoelastic NiTi alloy having a phase transition temperature above body temperature, a cobalt, nickel, molybdenum, and chromium alloy such as MP35N.
In a presently preferred embodiment of the invention, the open-walled element is self expanding, so that the open-walled element assumes an unexpanded configuration in response to radially compressing force, and the expanded diameter configuration when the radially compressing force is removed. However, the open-walled element may be configured to expand in response to a radially expanding force.
One aspect of the invention involves a method of performing a medical procedure using the catheter of the invention. The method comprises positioning the catheter in a desired location within the patient""s body lumen, expanding at least a portion of the catheter tubular open-walled element to contact a wall defining the body lumen and secure the catheter therein, and performing the medical procedure. The catheter is released from the body lumen following the medical procedure by collapsing the open-walled element into the unexpanded diameter configuration.
A presently preferred embodiment of the method of the invention involves performing a perfusion procedure within the patient""s body lumen, including but not limited to retroperfusion of the heart, perfusion of the ascending aorta, and isolation of a dissection of the descending aorta. For example, in retroperfusion of the heart, using the present invention, the tubular open-walled element can be left outside the coronary sinus ostium, inside the right atrium, and the occluding member can be advanced into the sinus until achieving its closure. Therefore, unlike available retroplegia cannulae, the catheter of the invention allows retroperfusion of the middle cardiac vein, which provides full retroperfusion of the heart, including the right ventricle, otherwise left unprotected with current cannula designs.
The catheter of the invention, having an expandable open-walled element, allows for securing the catheter within a patient""s body lumen without occluding side branches intersecting the body lumen. In one embodiment of the invention, the catheter provides for cannulation of the body lumen, wherein the cannula can be displaced relative to the secured site to choose the optimal perfusion site. In another embodiment of the invention, the catheter provides for occlusion of the body lumen, and displacement of the occluding member relative to the secured site so that the optimal occlusion site can be selected. These and other advantages of the invention will become apparent from the following detailed description of the invention and accompanying exemplary figures.